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Heart attacks are one of the leading causes of death in the UK today, and thus a hugely important challenge for healthcare research. Current treatments for individuals who survive heart attacks are designed to limit the injury already sustained and prevent any further complications. However, the goal for any future treatment will be the restoration of cardiac function via regeneration of damaged cardiac tissue. The hope is that stem cell treatment will be able to provide this in the future, but as yet there has been little progress.
Research published in The Lancet this week has shown early promise for stem cell treatment after myocardial infarction. Raj Makkar and colleagues’ research was a Phase I proof of principle study, with the primary aim of establishing the safety of stem cell treatment in a small number of patients, thus paving the way for larger studies to be carried out in the future.
The study looked at patients who had recently suffered a myocardial infarction (when blood flow to the heart is blocked for long enough for cardiac muscle to be damaged or die) and treated them with Cardiosphere-derived cells (CDCs), stem cells that were taken from a biopsy of each patient’s own cardiac muscle at the beginning of the study.
The study took 25 patients with 17 receiving CDCs and 8 the standard treatment. The CDCs were administered via an angioplasty catheter—a wire inserted down the blood vessels and inflated at the site of scar tissue (cardiac tissue damaged by the myocardial infarction). Patients were followed up regularly over a period of 6 months and then again after 12 months. Although one CDC patient suffered another heart attack and two were placed on defibrillators, there was no significant difference in safety between the CDC treatment and standard care, and no adverse effects were seen immediately after the administration of CDCs. However, more encouraging were the small signs of improvement in cardiac structure and function observed during the study. Scar tissue was observed using MRI and made up an average of 24% of cardiac tissue in patients at the beginning of the study; while this figure remained unchanged in controls, scar tissue had decreased by an average of 42% in the CDC group. An increase in viable heart mass and regional contractility was also observed, although end-diastolic and systolic volume had not changed.
While this study is a small phase I trial, it has shown encouraging signs that treatment for myocardial infarction with CDCs could be clinically viable, whereas previous studies using other types of cells such as bone marrow mononuclear cells and c-kit-positive cells have produced less promising results. The study seems to show that CDC treatment is safe in human patients and has shown some signs of clinical efficacy, albeit in a small number of patients, raising hope that treatment with CDCs could be successful in larger clinical trials.
While this is a good example of an early phase I study, the small numbers of patients and early nature of the research necessitates caution in interpreting its results. Future studies will need to use a larger population and longer follow-up to fully establish clinical efficacy and a definite improvement in the quality of life as a result of this treatment. However, this study has suggested that the treatment could be useful clinically, and future studies will be awaited with interest.
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